Method for writing data to an electrophoretic display panel

Abstract

A method for writing data to an EPID display includes loading data for a line of pixels onto the grid lines of the EPID. Instead of writing that single line fully by enabling the associated cathode row with a logical "1" voltage for the time necessary to cause complete pigment particle migration, the associated cathode line and at least the next adjacent cathode line are enabled for a shorter duration than is required for fully writing the lines. The grid is then loaded with data corresponding to the next line of pixels and the set of cathode lines enabled is shifted by one line, such that at least one cathode line previously enabled is enabled for a subsequent time whereby particle migration for writing is made more complete where the grid data is constant from one row of pixels to the next.

We claim: 
     
       1. A method for decreasing the time to write a frame of display data composed of a plurality of lines of displayable pixels on an electrophoretic display requiring a minimum time period for a line to be fully written comprising the following steps: (a) selecting a shortened period which is shorter in duration than said minimum period;   (b) writing a line set of at least two adjacent lines in said shortened period;   (c) shifting the lines of said line set such that said line set contains at least one new line and at least one old line;   (d) writing said shifted line set in a subsequent shortened period following said step of shifting; and   (e) repeating steps (c) and (d) until said frame is completely written.   
     
     
       2. The method of claim 1, wherein said shortened period is shorter when the number of lines in said line set is greater. 
     
     
       3. The method of claim 2, wherein said shortened period approximates said minimum period divided by the number of lines in said line set. 
     
     
       4. The method of claim 1, wherein said pixels of said old line are written darker when said new line contains pixels of an equal displacement from a common reference line. 
     
     
       5. The method of claim 4, wherein said darker written pixels are written with an intensity approximating the intensity of a pixel written for said minimum period. 
     
     
       6. The method of claim 5, further including the step of selecting the number of lines in said line set. 
     
     
       7. The method of claim 6, further including the step of adjusting said shortened period when a change in the number of lines in said line set occurs. 
     
     
       8. The method of claim 5, wherein said reference line is located on an edge of said display. 
     
     
       9. A method for operating an electrophoretic display of the type having a first plurality of parallel conductive lines disposed within a first plane and a second plurality of parallel conductive lines disposed within a second plane insulated from said first plurality, said first and said second plane being substantially parallel and said first and said second plurality being substantially perpendicular to form an X-Y addressing matrix, said display having a conventional anode electrode separated from said X-Y matrix with the space therebetween accommodating an electrophoretic dispersion including pigment particles suspended in a fluid, each of said first and said second plurality being selectively electrically chargeable to create a voltage gradient at each of said intersections of said X-Y matrix in conjunction with said anode to cause a localized migration of pigment particles relative to said intersections, said intersections constituting displayable pixels, comprises the following steps in substantially the following order: (a) selectively electrically charging each of said first plurality of lines with a first set of voltage levels;   (b) while said first plurality remains electrically charged, simultaneously electrically charging a set of 2 or more adjacent lines of said second plurality of lines for a selected period such that said pigment particles are caused either to migrate or not to migrate proximate said intersections associated with said 2 or more adjacent lines depending upon said voltage levels applied to each said line of said first plurality of lines;   (c) shifting the elements of said set by one adjacent line, such that the same number of elements are present in said set but the content of said set excludes at least one previously included element and includes at least one common element which was previously included in said set prior to shifting and one new element which is a line adjacent to said at least one common element;   (d) selectively electrically charging each of said first plurality of lines with a second set of voltage levels; and   (e) repeating steps (b) through (d) substituting subsequent sets of voltage levels in step (d) until all said pixels at said intersections of said X-Y matrix have been placed in a selected display state.   
     
     
       10. The method of claim 9, wherein said selected period is less than a normal writing period for fully writing a line of said pixels. 
     
     
       11. The method of claim 10, wherein said selected period becomes less when said set of 2 or more adjacent lines has more members. 
     
     
       12. The method of claim 11, wherein said selected period approximates the period associated with a normal write cycle period divided by the number of lines in said set of adjacent lines. 
     
     
       13. The method of claim 12, further including the step of selecting the number of lines in said set of adjacent lines. 
     
     
       14. The method of claim 13, further including the step of adjusting said selected period when a change in the number of lines in said set of adjacent lines occurs during said step of selecting the number of lines. 
     
     
       15. The method of claim 14, wherein said first plurality of lines are the grid lines of a triode-type EPID display. 
     
     
       16. The method of claim 15, wherein said second plurality of lines are the cathode lines of a triode-type EPID. 
     
     
       17. The method of claim 9, wherein said step of selectively electrically charging each of said first plurality of lines of step (a) is the loading of display data expressed as said set of voltage levels onto said grid lines. 
     
     
       18. The method of claim 9, wherein said step of simultaneously electrically charging a set of 2 or more adjacent lines is impressing a write enabling voltage on said adjacent lines, said write enabling voltage having a logical value of "1" and an operational value of "ON". 
     
     
       19. The method of claim 18, wherein said voltage levels in said voltage level set may assume either of at least two voltages, a first voltage having a logical value of "1" and an operational value of "ON" or a second voltage having a logical value of "0" and an operational value of "OFF". 
     
     
       20. The method of claim 19, wherein said pigment particles migrate in a direction leading to the display of a pixel located at said intersections where a line of said first plurality of lines and a line of said second plurality of lines both have a logical value of "1" simultaneously. 
     
     
       21. The method of claim 20, wherein said set of 2 or more lines contains 2 lines. 
     
     
       22. The method of claim 21, wherein said set of 2 lines is cathode line 1 and cathode line 2 starting at the top of said display during the first performance of steps b through d, cathode line 2 and cathode line 3 during the first repetition of steps (b) through (d), and cathode line 3 and cathode line 4 during the second repetition. 
     
     
       23. The method of claim 20, wherein said set of 2 or more lines contains 3 lines. 
     
     
       24. The method of claim 23, wherein said set of 3 lines is cathode lines 1, 2 and 3 starting at the top of said display during the first performance of steps b through d, cathode lines 2, 3 and 4 during the first repetition of steps (b) through (d), and cathode lines 3, 4 and 5 during the second repetition. 
     
     
       25. The method of claim 20, wherein said set of 2 or more lines contains 4 lines. 
     
     
       26. The method of claim 25, wherein said set of 4 lines is cathode lines 1, 2, 3 and 4 starting at the top of said display during the first performance of steps b through d, cathode lines 2, 3, 4 and 5 during the first repetition of steps (b) through (d), and cathode lines 3, 4, 5 and 6 during the second repetition.